Methodology

Exposure score

For each material and selected country:

exposure = 0.4 * norm(HHI)
         + 0.35 * importReliance
         + 0.25 * (1 - norm(reserveLife, capped at 100y))

HHI is normalised by dividing by 10,000. Import reliance is already a percentage, divided by 100. Reserve life is min(years, 100) / 100. Weights live in lib/config.ts. If any of the three inputs is missing, the score is shown as No data — never filled with zero.

HHI and reserve life

Supply concentration is the Herfindahl-Hirschman Index of listed country production: the sum of squared shares of the USGS country rows, times 10,000. “Other countries” is one bucket, as published. Shares use the sum of listed country rows, not the independently rounded world total.

Reserve life is global reserves ÷ annual global production. It is labelled “known reserves cover ~X years at current production”, not a depletion date, and not “runs out in X years”.

Supplier shock

Lost share is the shocked supplier’s listed production divided by listed world production. China or Russia alone is that one country. China and Russia together sums both. BRICS sums Brazil, Russia, India, China, South Africa, Egypt, Ethiopia, Iran, the UAE and Indonesia — including China and Russia. A material is flagged severe if lost share is greater than 50% and import reliance is greater than 70%. This is a simple illustration: no rerouting, stockpiles or substitution.

Sources

• USGS Mineral Commodity Summaries 2026 — mine/refinery production, reserves, US net import reliance, uses, recycling and substitution notes. Public domain USGS data.
• EU import reliance and CRM membership: Study on the Critical Raw Materials for the EU 2023. Licence: EU reuse policy / official publication.
• US list: Final 2025 List of Critical Minerals, 90 FR 50494.

Known gaps

• High-purity quartz and rhodium have no USGS country production table. Germanium has no published country table.
• Gallium, indium and some others are refinery or byproduct statistics, not mine output.
• USGS values reported as >50% or withheld are shown as No data, not as 50 or 0.
• Map uses Natural Earth 110m via world-atlas (public domain / Natural Earth terms). Conflict overlays are off and not included in v1.